Federal and state environmental officials are investigating whether a possible discharge of water from an old mine site killed fish in Boulder County.
"We've collected water quality samples to submit to the laboratory for analysis but we haven't determined whether or not the Superfund site has impacted the fish or if there was some other cause," said Mary Boardman, with the state health department.
It happened downstream of the Captain Jack Mill Superfund site.
The number of fish killed is unknown at this time but is estimated to be in the low 100s. The fish were found dead in the upper portions of Left Hand Creek.
The Daily Camera reports that Colorado Parks and Wildlife staff were notified by a local resident that the water was turning orange. Upon investigation a retention pond with dead fish was found further up stream.
The Left Hand Water District, which has a drinking water intake approximately 15 miles downstream, has been notified. Both raw and treated water are tested on a continuous basis, but as a cautionary measure the district shut off the intake from Left Hand Creek while tests of the water were being conducted. The intake has since been reopened, following test results that met water quality standards.
The state health department and Environmental Protection Agency have been addressing contamination associated with historic mining operations at the Captain Jack Mill Superfund site since 1986. It was added to the Superfund National Priorities List Sept. 29, 2003.